ref: c76cc12a1799ce214b07882eb6f4ab0906c0151b
dir: /sys/src/cmd/gs/jpeg/jdinput.c/
/* * jdinput.c * * Copyright (C) 1991-1997, Thomas G. Lane. * This file is part of the Independent JPEG Group's software. * For conditions of distribution and use, see the accompanying README file. * * This file contains input control logic for the JPEG decompressor. * These routines are concerned with controlling the decompressor's input * processing (marker reading and coefficient decoding). The actual input * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c. */ #define JPEG_INTERNALS #include "jinclude.h" #include "jpeglib.h" /* Private state */ typedef struct { struct jpeg_input_controller pub; /* public fields */ boolean inheaders; /* TRUE until first SOS is reached */ } my_input_controller; typedef my_input_controller * my_inputctl_ptr; /* Forward declarations */ METHODDEF(int) consume_markers JPP((j_decompress_ptr cinfo)); /* * Routines to calculate various quantities related to the size of the image. */ LOCAL(void) initial_setup (j_decompress_ptr cinfo) /* Called once, when first SOS marker is reached */ { int ci; jpeg_component_info *compptr; /* Make sure image isn't bigger than I can handle */ if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION || (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION) ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION); /* For now, precision must match compiled-in value... */ if (cinfo->data_precision != BITS_IN_JSAMPLE) ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); /* Check that number of components won't exceed internal array sizes */ if (cinfo->num_components > MAX_COMPONENTS) ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components, MAX_COMPONENTS); /* Compute maximum sampling factors; check factor validity */ cinfo->max_h_samp_factor = 1; cinfo->max_v_samp_factor = 1; for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR || compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR) ERREXIT(cinfo, JERR_BAD_SAMPLING); cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor, compptr->h_samp_factor); cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor, compptr->v_samp_factor); } /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE. * In the full decompressor, this will be overridden by jdmaster.c; * but in the transcoder, jdmaster.c is not used, so we must do it here. */ cinfo->min_DCT_scaled_size = DCTSIZE; /* Compute dimensions of components */ for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++) { compptr->DCT_scaled_size = DCTSIZE; /* Size in DCT blocks */ compptr->width_in_blocks = (JDIMENSION) jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, (long) (cinfo->max_h_samp_factor * DCTSIZE)); compptr->height_in_blocks = (JDIMENSION) jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, (long) (cinfo->max_v_samp_factor * DCTSIZE)); /* downsampled_width and downsampled_height will also be overridden by * jdmaster.c if we are doing full decompression. The transcoder library * doesn't use these values, but the calling application might. */ /* Size in samples */ compptr->downsampled_width = (JDIMENSION) jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor, (long) cinfo->max_h_samp_factor); compptr->downsampled_height = (JDIMENSION) jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor, (long) cinfo->max_v_samp_factor); /* Mark component needed, until color conversion says otherwise */ compptr->component_needed = TRUE; /* Mark no quantization table yet saved for component */ compptr->quant_table = NULL; } /* Compute number of fully interleaved MCU rows. */ cinfo->total_iMCU_rows = (JDIMENSION) jdiv_round_up((long) cinfo->image_height, (long) (cinfo->max_v_samp_factor*DCTSIZE)); /* Decide whether file contains multiple scans */ if (cinfo->comps_in_scan < cinfo->num_components || cinfo->progressive_mode) cinfo->inputctl->has_multiple_scans = TRUE; else cinfo->inputctl->has_multiple_scans = FALSE; } LOCAL(void) per_scan_setup (j_decompress_ptr cinfo) /* Do computations that are needed before processing a JPEG scan */ /* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */ { int ci, mcublks, tmp; jpeg_component_info *compptr; if (cinfo->comps_in_scan == 1) { /* Noninterleaved (single-component) scan */ compptr = cinfo->cur_comp_info[0]; /* Overall image size in MCUs */ cinfo->MCUs_per_row = compptr->width_in_blocks; cinfo->MCU_rows_in_scan = compptr->height_in_blocks; /* For noninterleaved scan, always one block per MCU */ compptr->MCU_width = 1; compptr->MCU_height = 1; compptr->MCU_blocks = 1; compptr->MCU_sample_width = compptr->DCT_scaled_size; compptr->last_col_width = 1; /* For noninterleaved scans, it is convenient to define last_row_height * as the number of block rows present in the last iMCU row. */ tmp = (int) (compptr->height_in_blocks % compptr->v_samp_factor); if (tmp == 0) tmp = compptr->v_samp_factor; compptr->last_row_height = tmp; /* Prepare array describing MCU composition */ cinfo->blocks_in_MCU = 1; cinfo->MCU_membership[0] = 0; } else { /* Interleaved (multi-component) scan */ if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN) ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan, MAX_COMPS_IN_SCAN); /* Overall image size in MCUs */ cinfo->MCUs_per_row = (JDIMENSION) jdiv_round_up((long) cinfo->image_width, (long) (cinfo->max_h_samp_factor*DCTSIZE)); cinfo->MCU_rows_in_scan = (JDIMENSION) jdiv_round_up((long) cinfo->image_height, (long) (cinfo->max_v_samp_factor*DCTSIZE)); cinfo->blocks_in_MCU = 0; for (ci = 0; ci < cinfo->comps_in_scan; ci++) { compptr = cinfo->cur_comp_info[ci]; /* Sampling factors give # of blocks of component in each MCU */ compptr->MCU_width = compptr->h_samp_factor; compptr->MCU_height = compptr->v_samp_factor; compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height; compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size; /* Figure number of non-dummy blocks in last MCU column & row */ tmp = (int) (compptr->width_in_blocks % compptr->MCU_width); if (tmp == 0) tmp = compptr->MCU_width; compptr->last_col_width = tmp; tmp = (int) (compptr->height_in_blocks % compptr->MCU_height); if (tmp == 0) tmp = compptr->MCU_height; compptr->last_row_height = tmp; /* Prepare array describing MCU composition */ mcublks = compptr->MCU_blocks; if (cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU) ERREXIT(cinfo, JERR_BAD_MCU_SIZE); while (mcublks-- > 0) { cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci; } } } } /* * Save away a copy of the Q-table referenced by each component present * in the current scan, unless already saved during a prior scan. * * In a multiple-scan JPEG file, the encoder could assign different components * the same Q-table slot number, but change table definitions between scans * so that each component uses a different Q-table. (The IJG encoder is not * currently capable of doing this, but other encoders might.) Since we want * to be able to dequantize all the components at the end of the file, this * means that we have to save away the table actually used for each component. * We do this by copying the table at the start of the first scan containing * the component. * The JPEG spec prohibits the encoder from changing the contents of a Q-table * slot between scans of a component using that slot. If the encoder does so * anyway, this decoder will simply use the Q-table values that were current * at the start of the first scan for the component. * * The decompressor output side looks only at the saved quant tables, * not at the current Q-table slots. */ LOCAL(void) latch_quant_tables (j_decompress_ptr cinfo) { int ci, qtblno; jpeg_component_info *compptr; JQUANT_TBL * qtbl; for (ci = 0; ci < cinfo->comps_in_scan; ci++) { compptr = cinfo->cur_comp_info[ci]; /* No work if we already saved Q-table for this component */ if (compptr->quant_table != NULL) continue; /* Make sure specified quantization table is present */ qtblno = compptr->quant_tbl_no; if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || cinfo->quant_tbl_ptrs[qtblno] == NULL) ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); /* OK, save away the quantization table */ qtbl = (JQUANT_TBL *) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(JQUANT_TBL)); MEMCOPY(qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF(JQUANT_TBL)); compptr->quant_table = qtbl; } } /* * Initialize the input modules to read a scan of compressed data. * The first call to this is done by jdmaster.c after initializing * the entire decompressor (during jpeg_start_decompress). * Subsequent calls come from consume_markers, below. */ METHODDEF(void) start_input_pass (j_decompress_ptr cinfo) { per_scan_setup(cinfo); latch_quant_tables(cinfo); (*cinfo->entropy->start_pass) (cinfo); (*cinfo->coef->start_input_pass) (cinfo); cinfo->inputctl->consume_input = cinfo->coef->consume_data; } /* * Finish up after inputting a compressed-data scan. * This is called by the coefficient controller after it's read all * the expected data of the scan. */ METHODDEF(void) finish_input_pass (j_decompress_ptr cinfo) { cinfo->inputctl->consume_input = consume_markers; } /* * Read JPEG markers before, between, or after compressed-data scans. * Change state as necessary when a new scan is reached. * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI. * * The consume_input method pointer points either here or to the * coefficient controller's consume_data routine, depending on whether * we are reading a compressed data segment or inter-segment markers. */ METHODDEF(int) consume_markers (j_decompress_ptr cinfo) { my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; int val; if (inputctl->pub.eoi_reached) /* After hitting EOI, read no further */ return JPEG_REACHED_EOI; val = (*cinfo->marker->read_markers) (cinfo); switch (val) { case JPEG_REACHED_SOS: /* Found SOS */ if (inputctl->inheaders) { /* 1st SOS */ initial_setup(cinfo); inputctl->inheaders = FALSE; /* Note: start_input_pass must be called by jdmaster.c * before any more input can be consumed. jdapimin.c is * responsible for enforcing this sequencing. */ } else { /* 2nd or later SOS marker */ if (! inputctl->pub.has_multiple_scans) ERREXIT(cinfo, JERR_EOI_EXPECTED); /* Oops, I wasn't expecting this! */ start_input_pass(cinfo); } break; case JPEG_REACHED_EOI: /* Found EOI */ inputctl->pub.eoi_reached = TRUE; if (inputctl->inheaders) { /* Tables-only datastream, apparently */ if (cinfo->marker->saw_SOF) ERREXIT(cinfo, JERR_SOF_NO_SOS); } else { /* Prevent infinite loop in coef ctlr's decompress_data routine * if user set output_scan_number larger than number of scans. */ if (cinfo->output_scan_number > cinfo->input_scan_number) cinfo->output_scan_number = cinfo->input_scan_number; } break; case JPEG_SUSPENDED: break; } return val; } /* * Reset state to begin a fresh datastream. */ METHODDEF(void) reset_input_controller (j_decompress_ptr cinfo) { my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl; inputctl->pub.consume_input = consume_markers; inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ inputctl->pub.eoi_reached = FALSE; inputctl->inheaders = TRUE; /* Reset other modules */ (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo); (*cinfo->marker->reset_marker_reader) (cinfo); /* Reset progression state -- would be cleaner if entropy decoder did this */ cinfo->coef_bits = NULL; } /* * Initialize the input controller module. * This is called only once, when the decompression object is created. */ GLOBAL(void) jinit_input_controller (j_decompress_ptr cinfo) { my_inputctl_ptr inputctl; /* Create subobject in permanent pool */ inputctl = (my_inputctl_ptr) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_PERMANENT, SIZEOF(my_input_controller)); cinfo->inputctl = (struct jpeg_input_controller *) inputctl; /* Initialize method pointers */ inputctl->pub.consume_input = consume_markers; inputctl->pub.reset_input_controller = reset_input_controller; inputctl->pub.start_input_pass = start_input_pass; inputctl->pub.finish_input_pass = finish_input_pass; /* Initialize state: can't use reset_input_controller since we don't * want to try to reset other modules yet. */ inputctl->pub.has_multiple_scans = FALSE; /* "unknown" would be better */ inputctl->pub.eoi_reached = FALSE; inputctl->inheaders = TRUE; }